PROJECTSUMMARY(CHEN,JI) Primaryciliaarethe?cellularantennae?thatdetectvariousextracellularsignalsincludinghormones.Defectsin primaryciliacauseabroadspectrumofhumandiseasesincludingobesity.Thetype3adenylylcyclase(AC3) isthemajoradenylylcyclaseandakeyenzymemediatingthecAMPsignalpathwayinolfactorysensorycilia andinprimaryciliathroughoutthecentralnervoussystem(CNS).AC3inolfactorysensoryciliaisessentialfor theolfactorysignaltransductionandlossofAC3leadstoanosmia(lossofsmell).Moreover,multiplegenetic evidencehasdemonstratedthatdefectsinAC3areassociatedwithobesityanddepression.Nevertheless,the functionalmechanismsofAC3,andthesignalingtransductionpathwayinprimaryciliaintheCNSremaintobe elucidated.Becauseolfactorysensoryciliaandneuronalprimaryciliaarestructurallyrelatedandsharea commonintraflagellarproteintransportsystem,wehypothesizethatthecAMPsignalingintheprimaryciliaof CNSneuronsresemblesthatinolfactorysensoryciliaandalterationofthissignalinginneuronalprimarycilia impactsobesityanddepression.Totestthishypothesis,wewillfirstusefluorescentnanoparticlesinco- immnunostainingexperimentsandtakeamassspectrometrybasedproteomicapproachtoidentifysignal proteinsthattransducethecAMPsignalingintheprimaryciliaofCNSneurons.Wewillnextgenetically engineeralight-activatedadenylylcyclaseintoprimaryciliatoenableoptogeneticmanipulationofcAMPlevel inneuronalprimarycilia.WewillalsodeterminehowcAMPinneuronalprimaryciliamodulateneuronal functions.Inaddition,wewillfurtheridentifywhichneuronalensembleswithlossofAC3leadstoobesityand depressionusingtissue-specificAC3knockoutmice.Completionofthisprojectwillidentifymolecular componentsthatmediateciliarycAMPsignaltransduction,generateusefultoolsforciliumresearch,and providenovelinsightsintothe(patho-)physiologicalrolesofAC3inobesityanddepression.